Regular Article

Material dependence on the mean charge state of light ions in titanium, zirconium and copper

¹ The University of Manchester, School of Chemistry, Oxford Road, Manchester M13 9PL, UK
² University of Notre Dame, Radiation Laboratory, Notre Dame, IN 46556, USA
³ University of Notre Dame, Department of Physics, Notre Dame, IN 46556, USA
⁴ The Joint Institute for Nuclear Astrophysics: CEE, Michigan State University, East Lansing, MI 48824, USA
⁵ Idaho National Laboratory, P.O. Box 1625, M.S. 3553, Idaho Falls, ID 83415, USA

^a e-mail: jay.a.laverne.1@nd.edu

Received: 14 March 2019
Received in final form: 13 June 2019
Published online: 17 October 2019

Abstract

Charge cycling cross sections of lithium and helium ions are measured for atomic metal films of titanium, zirconium and copper. The material dependence of the measured charge state fractions is investigated and compared with the material density, electron density, mean ionization potential and Fermi level. The experimental data quantitatively agrees with previously documented charge exchange cross sections for thin films and shows the expected increase in the fraction of higher charge states with increasing velocity, over the ion velocity range considered. There is an observable material dependence of the charge state fraction. The measured charge state distributions are expressed as a mean charge state and compared with various mean and effective charge formalisms. The effective charge models are demonstrated to be inadequate representations of the measured mean charge states for the ions and films probed in this study.